Patent document WO200058642 for example discloses an aircraft landing gear comprising:                an axle shaft designed to carry at least one wheel via which the aircraft runs along the ground;        a strut extending along a main strut axis and having a first part carrying the said axle shaft and a second part designed to be connected to a bearing structure belonging to the aircraft, the said main strut axis passing through these first and second strut parts;        a main damper designed to damp axial movements of the first strut part with respect to the second strut part;        a first secondary damper distinct from the said main damper and designed to damp a movement of angular oscillation, about the main strut axis, of the first strut part with respect to the second strut part.        
The bearing structure of the aircraft is the aircraft structure to which the landing gear is attached for transferring load between the landing gear and the rest of the aircraft.
When the landing gear is running, vibratory/oscillatory phenomena referred to as shimmy may appear between the first and second strut parts. This phenomenon of shimmy includes at least one rotational oscillation, about the main axis of the landing gear, of the first landing gear part with respect to the second landing gear part. This rotational oscillation is generated by torsion of the strut about its main axis. Other vibratory/oscillatory phenomena may be added to this rotational oscillation. In particular, the shimmy phenomenon frequently combines oscillations of the strut in longitudinal bending with oscillations in rotation about the main strut axis.
These vibratory phenomena create discomfort and it is desirable to eliminate them.
These vibratory/oscillatory phenomena are dependent on several factors such as the load on the landing gear, its shape, its design, its flexibility and the running speed.
In order to lessen this phenomenon, patent document WO200058642 suggests fitting a specific damper, referred to as an anti-shimmy damper or, hereinafter, a secondary damper. In that patent document, the secondary damper couples the second strut part which is connected to the structure of the aircraft to the first part of the landing gear strut that carries the axle shaft. This mechanical coupling of the first and second strut parts via the secondary damper (the anti-shimmy damper) makes it possible to damp angular oscillations, about the main strut axis, of the first strut part with respect to the second strut part.
Incorporating this type of anti-shimmy damper into the geometry of the landing gear is problematic because this secondary damper needs to perform its damping function while at the same time allowing the landing gear to pass from a gear-down configuration outside the bay to a gear-up configuration in which the landing gear is retracted inside the bay.